Diagonally slice the unpeeled sweet potato into 1-cm thick rounds.
Soak the slices of sweet potato in a bowl of water for about 5 minutes. Drain and blot off excess moisture with a paper towel.
Shred the maitake into small clumps.
Combine the ★ ingredients to make the batter.
Deep fry in oil heated to 180℃.
Drain off the excess oil, transfer to a dish and serve. Serve it with tentsuyu or salt to taste.
Story Behind this Recipe
When I asked the soba shop the trick to making their tempura so crispy, they told me that they add vinegar to the batter and don't use eggs. I experimented with the proportions and came up with this recipe.
The batch of batter that you get from the amounts listed will be more than you need, so you can also fry up 1-2 more ingredients (such as shrimp). If you have a small amount to fry up, reduce the proportions accordingly.